Pesticide intermediates

ABSTRACT

A compound of the formula: ##STR1## wherein Y represents OH or a halogeno group; 
     D represents hydrogen or a cyano group; 
     B represents hydrogen or a methyl, ethyl or vinyl group; 
     A represents methyl; 
     n is 0, 1 or 2; 
     with the proviso that 
     (1) when the CH 2  CH═CHB group is in the 4-position with respect to the CHDY group, then D must be hydrogen and B must be methyl, ethyl or vinyl and the configuration about the double bond in the CH═CHB group must be Z and 
     (2) when the group CH═CHB is in the 3-position with respect to the CHDY group and D is CN then n must be 0 and 
     (3) when the group CH 2  CH═CHB is in the 2 or 3-position with respect to the CHDY group, then D is CN, are useful in the production of pesticidal esters of chrysanthemic and related acids.

This is a division, of application Ser. No. 517,393, filed July 26,1983, now U.S. Pat. No. 4,594,355.

This invention relates to pesticides and in particular to pesticidalcompounds, the preparation of such compounds, intermediates for use intheir prepraration, compositions containing such compounds and the useof such compounds and compositions to control pests, for example pestspresent in soil.

Accordingly the present invention comprises a compound of formula I##STR2## in which formula: D represents hydrogen or a cyano group or anethynyl group;

B represents hydrogen, alkyl or alkenyl;

A represents an alkyl group (typically a C₁ -C₆ alkyl group) or ahalogeno group e.g. F, Cl or Br or a CF₃ group;

n is 0 to 4;

RCOO represents a residue of a 2,2-dimethylcyclopropane carboxylic acidcarrying at the 3-position a dihalovinyl, alkenyl or carboalkoxyalkenylgroup;

provided that (1) when the group --CH₂ CH═CHB is located at the fourposition in the ring with respect to the ester linkage, then D must behydrogen and the group carried at the 3-position on the cyclopropanering of the acid must be a dihalovinyl group and (2) when the group--CH₂ CH═CHB is located at the 3-position in the ring and D represents acyano group, then n must be 0.

When the group at the 3-position of the cyclopropane ring is alkenyl orcarboalkoxyalkenyl, the alkenyl is an alkmonoenyl, usually branchchained such as isobutenyl or 2-methoxycarbonylpropenyl so that thepreferred acid residue of this type is of chrysanthemic acid, especiallywhen in the trans form and particularly when in the (IR,trans) form orpyrethric acid. The most preferred acids are2,2-dimethyl-3-(2,2-dihalovinyl)-cyclopropane carboxylic acids, the2,2-dimethyl-3-(2,2-dibromovinyl)-cyclopropane carboxylic acid,especially when in the (IR,cis) form being of particular interest.

When B represent an alkyl or alkenyl group the configuration about thethe double bond of the substituent --CH₂ CH═CHB can be E or Z andcompounds in which the configuration is Z are preferred as also aremixtures of geometrical isomers in which the Z isomer predominates.Compounds in which B represents methyl, ethyl or vinyl, are ofparticular interest, the latter especially so. The preferred position inthe ring with respect to the ester linkage for the substituent --CH₂CH═CHB is 3 or 4, the 3 position in compounds wherein D represents acyano group being of particular interest.

The group A, when present, is typically disposed at the 2 position inthe ring with respect to the ester linkage and if alkyl, generallyrepresents methyl. Two groups, e.g. methyl, groups, when present, areusually disposed at the 2,6 position in the ring with respect to theester link. Such compounds are of special interest when B in the group--CH₂ CH═CHB represents hydrogen, the group preferably being located atthe 3 or 4 position in the ring.

As hereinbefore described, esters I of a2,2-dimethyl-3-(dihalovinyl)-cyclopropane carboyxlic acid, typically anacid in which both halogens, whether fluorine, chlorine or bromine areidentical, are preferred and esters of2,2-dimethyl-3-(dibromovinyl)-cyclopropane carboxylic acid especiallyso. The following esters of the latter acid, especially when in the (IRcis) form are of particular interest: α-cyano-3-allyl-benzyl(D=CN, B=H);α-cyano-3-methylallyl benzyl (D=CN, B=CH₃); 3-methylallyl benzyl (D=H,B=CH₃); 3-pentadienyl- and 4-pentadienyl benzyl (D=H, B=--CH═CH₂);α-cyano-3-pentadienyl benzyl), α-cyano-3-ethylallyl benzyl (D=CN,B=--CH₂ CH₃) 2-methyl-3-allylbenzyl (D=H, B=H, A=CH₃ n=1);2,6-dimethyl-4-allyl-benzyl (D=H, B=H, A=CH₃ n=2) it being highlypreferred that the latter compounds, where possible, exist in the Zconfiguration.

Esters I may be prepared by reaction of an acid RCOOH or anester-forming derivative thereof with an intermediate of formula II##STR3## wherein Y represents a hydroxyl or halogen e.g. chlorine, andD, A, n and B are as defined above.

Intermediates of formula II, are also included in a further aspect ofthe present invention, provided that (1) when the group --CH₂ CH═CHB isdisposed at the 4 position in the ring with respect to the --CHDY groupthen D must be hydrogen and B must be alkyl or alkenyl and theconfiguration about the double bond in the group must be Z, and providedthat (2) when the group --CH₂ CH═CHB is disposed at the 3 position withrespect to the CHDY group and D represents a cyano group, then n must be0.

It is generally preferred for the configuration about the double bond inintermediates II to be Z and the following compounds are of particularinterest:

(a) II, D=H, n=0, B=--CH═CH₂, Z isomer, ring position 3

(b) II, D=H, n=0, B=--CH═CH₂, E isomer ring position 3

(c) II, D=CN, n=0, B=--CH═CH₂, Z isomer, ring position 3

(d) II, D=H, n=0, B=--CH═CH₂, Z isomer, ring position 4

(e) II, D=H, n=0, B=--CH₃, Z isomer, ring position 3

(f) II, D=CN, n=0, B=--CH₃, Z isomer, ring position 3

(g) II, D=CN, B=--CH₂ CH₃, Z isomer, ring position 3

(h) D=H, n=1, A=CH₃ at ring position 2, B=H at ring position 3. In thelatter compounds Y typically represents a hydroxyl group.

The production of intermediates of formula II in which n=O isillustrated by the following reaction schemes. Intermediates where n=1-4are obtainable starting from the appropriately ring substitutedreactant. ##STR4##

Intermediate cyanohydrins or ethynyl compounds (II, Y=OH, D=CN or C=CH)are generally produced from the corresponding aldehydes by treatmentthereof with an alkali metal cyanide suitably under acid conditions orusing a magnesium acetylide. The required aldehydes are usually obtainedby pyridinium dichromate oxidation of the corresponding alcoholsproduced by methods analogous to those shown in the schemes above.

Intermediates II in which Y represents halogen and D represents hydrogenmay be produced from intermediates II in which Y represents -OH and Drepresents hydrogen, in accordance with a further aspect of the presentinvention by treatment of the latter intermediates with a halogenatingreagent of the class employed for conversion of carboxylic acids to acylhalides e.g. SO(hal)₂, typically with pyridine or P(hal)₃, halrepresenting chlorine or bromine.

As hereinbefore described the compounds of the present invention can beprepared by an esterification involving the reaction of an alcohol offormula II or an esterifiable derivative thereof with a carboxylic acidof formula RCOOH or an esterifiable derivative thereof. It is usuallyconvenient in practice to react an alcohol of formula II with an acylchloride of formula RCOCl or to react a salt of the carboxylic acid e.g.a silver or triethylammonium salt with a benzylhalide derivative, orcyanobenzyl halide which may be ring alkylated or to esterify thecarboxylic acid with the alcohol in the presence ofN,N-dicyclohexylcarbodiimide and a catalyst.

Alternatively, the esters of the invention can be prepared bytransesterification by reacting a C₁ -C₆ alkyl ester of the carboxylicacid with a benzyl alcohol of formula II in the presence of a basictransesterification catalyst. This method is not usually satisfactorywhere either molecule contains another base-sensitive residue, e.g.where the carboxylic acid is pyrethric acid.

The compounds of the invention exhibit optical isomerism in that thecarbon atom bearing the substitutent D can exist in the R or Sconfiguration and the present invention includes compounds in which theconfiguration is substantially completely R or in which theconfiguration is substantially completely S or mixtures thereof.

Compounds of the invention can exist in the form of both geometrical andoptical isomers. This is because of the unsymmetrical substitution at C₁and C₃ of the cyclopropane ring. Compounds of the present inventioninclude those isomers in which the hydrogen atoms at C₁ and C₃ of thecyclopropane ring are substantially completely in the cis configurationor substantially completely in the trans configuration or mixturesthereof. The present invention also includes compounds in which theconfiguration at C₁ is substantially completely R or substantiallycompletely S and mixtures thereof. In the compounds of the invention theoptical configuration at C₁ and C₃ cannot very independently of thegeometrical configuration of the hydrogen atoms at C₁ and C₃ of thecyclopropane ring. The effect of this is that the configuration of thecyclopropane ring can be defined uniquely by specifying the opticalconfiguration at C₁ and the geometrical configuration of the hydrogenatoms at C₁ and C₃ and, for definition purposes, we have adoptednomenclature of the form (IR)-cis, (IR)-trans etc. it being unnecessaryto specify the optical configuration at C₃ which is fixed once the othertwo variables are defined. Adopting this nomenclature avoids theconfusion which can arise by having to designate either R or S to thesame optical configuration at C₃ depending upon the nature of thesubstituents on the cyclopropane ring and even those on the side chain.

When R is a group in which the substitution about the ethylenic bond isasymmetrical, then the configuration of this part of the molecule can besubstantially completely in the E form or substantially completely inthe Z form or a mixture thereof.

The compounds of the present invention can be in the form of singleisomers but, having regard to the fact that the compounds have at leastone and frequently more than one centre of asymmetry, the compounds ofthe invention will normally be in the form of isomer mixtures, althoughthese isomer mixtures can be optically active and/or substantiallycompletely in one geometric form.

One or more of the pesticidal esters of formula I can be formulated withan inert carrier or diluent to give pesticidal compositions and suchcompositions form a further aspect of the present invention. Thesecompositions can be in the form of dusts and granular solids, wettablepowders, mosquito coils and other solid preparations, or as emulsions,emulsifiable concentrates, sprays and aerosols and other liquidpreparations after the addition of the appropriate solvents, diluentsand surface-active agents.

Compositions formulated in a manner suitable for controlling soil peststypically by treatment of the soild are of especial interest. For thispurpose compositions containing compounds I hereinbefore described areparticularly suitable as they generally have lower molecular weightsthan many previously described pyrethroids, and it is envisaged thattheir relatively high vapour pressures allow them to diffuse through thesoil.

The pesticidal compositions of the invention will normally contain from0.001 to 25% by weight of the compound of formula I but the compositionscan contain higher concentrations of active ingredient of formula I e.g.up to 95 % for compositions to be sold as concentrates for dilutionbefore use by the ultimate user.

The compositions of the invention can include diluents such ashydrocarbon oils, e.g. xylene or other petroleum fractions, water,anionic, cationic or non-ionic surface-active agents, anti-oxidants andother stabilisers as well as perfumes and colouring matters. These inertingredients may be of the type and in proportions such as areconventionally used in pesticidal compositions containingpyrethroid-like compounds.

In addition to these inactive ingredients, the compositions of thepresent invention may contain one or more further active ingredientswhich may be other pesticidal compounds of the pyrethroid type or ofother types and the composition may also include synergists of the typeknown to be capable of synergising the activity of natural pyrethrin andpyrethroid-like insecticides. Synergists of this type include piperonylbutoxide, tropital and sesamex.

The compounds of formula I can be used to control pest infestation inthe domestic, horticultural or agricultural or medical, includingveterinary, areas. The compounds or compositions of the invention can beused to combat pest infestation by tresting pests or surfaces orenvironments susceptible to pest infestation with effective amounts ofthe active compounds of formula I or of compositions containing them.For example, they may be used in a domestic environment for sprayingrooms to combat infestation with houseflies or other insects, they canbe used for treatment of stored dry crops or cereals to combatinfestation by insects or other pests, they can be used to spray growingcrops, e.g. cotton or rice to combat infestation by common pests andthey can be used in a medical or veterinary field, e.g. as a cattlespray to prevent or treat infestation by insects or other pests.

Although, as hereinbefore indicated, they are of particular interest forthe disinfestation of soil to control pests such as the onionfly, Deliaantiqua, the wheat bulb fly, Delia coarctata the compounds may findapplication in the control of a wide variety of pests including:

from the class of the Isopoda, for example Oniscus asellus,Armadillidium vulgare and Porcellio scaber;

from the class of the Diplopoda, for example Blaniulus guttulatus;

from the class of the Chilopoda, for example Geophilus carpophagus andScutigera spec.;

from the class of the Symphyla, for example Scutigerella immaculata;

from the order of the Thysanura, for example Lepisma saccharina;

from the order of the Collembola, for example Onychiurus armatus;

from the order of the orthoptera, for example Blatta orientalis,Periplaneta americana, Leucophaea madarae, Blattela germanica, Achetadomesticus, Gryllotalpa spp., Locusta migratoria migratorioides,Melanoplus differentialis and Schistocerca gregaria;

from the order of the Dermaptera, for example Forficula auricularia;

from the order of the Isoptera, for example Reticulitermes spp.;

from the order of the Anoplura, for example Phylloxera vastatrix,Pemphigus spp., Pediculus humanus corporis, Haematopinus spp. andLinognathus spp.;

from the order of the Mallophaga, for example Trichodectes spp. andDemalinea spp.;

from the order of the Thysanoptera, for example Hercinothrips femoralisand Thrips tabaci;

from the order of the Heteroptera, for example Eurygaster spp.,Dysdercus intermedius, Piesma quadrata, Cimex lectularius, Rhodniusprolius and Triatoma spp.;

from the order of the Homoptera, for example Aleurodes brassicae,Bemisia tabaci, Trialeurodes vaporariorum, Aphis gossypii, Brevicorynebrassicae, Cryptomyzus ribis, Doralis fabae, Doralis pomi, Eriosomalanigerum, Hyalopterus arundinis, Macrosiphum avenae, Myzus spp.,Phorodon humuli, Rhopalosiphum padi, Empoasca spp., Euscelis bilobatus,Nephotettix cincticeps, Lecanium corni, Saissetia oleae, Laodelphaxstriatellus, Nilaparvata lugens, Aondiiella aurantii, Aspidiotushederae, Pseudococcus spp. and Psylla spp.;

from the order of the Lepidoptera, for example Pectinophora gossypiella,Bupalus piniarius, Cheimatobia brumata, Lithocolletis blancardella,Hyponomeuta padella, Plutella maculipennis, Malacosoma neustria,Euproctis chrysorrhoea, Lymantria spp., Bucculatrix thurberiella,Phyllocnistis citrella, Agrotis supp., Euxoa spp., Feltia spp., Eariainsulana, Heliothis spp., Laphygma exigua, Mamestra brassicae, Panolisflammea, Prodenia litura, Spodoptera spp., Trichoplusia ni, Carposcapsapomonella, Pieris spp., Chilo spp., Pyrausta nubilalis, Ephestiakuehniella, Galleria mellonella, Cacoecia podana, Capua reticulana,Choristoneura fumiferana, Clysia ambiguella, Homona magnanima andTortrix viridana;

from the order of the Coleoptera, for example Anobium punctatum,Rhizopertha dominica, Bruchidius obtectus, Acanthoscelides obtectus,Hylotrupes bajulus, Agelastica alni, Leptinotarsa decemlineata, Phaedoncochleariae, Diabrotica spp., Psylliodes chrysocephala, Epilachnavarivestis, Atomaria spp., Oryzaephilus surinamensis, Anthonomus spp.,Sitophilus spp., Otiorrhynchus sulcatus, Cosmopolites sordidus,Ceuthorrhynchus assimilis, Hypera positica, Dermestes spp., Trogodermaspp., Anthrenus spp., Attagenus spp., Lyctus spp., Meligethes aeneus,Ptinus spp., Niptus hololeucus, Gibbium psylloides, Tribolium spp.,Tenebrio molitor, Agriotes spp., Conoderus spp., Melolontha melolntha,Amphimallon solsti tialis and Costelytra zealandica;

from the order of the Hymenoptera, for example Diprion spp., Hoplacampaspp., Lasius spp., Monomorium pharaonis and Vespa spp.,

from the order of the Diptera, for example Aedes spp., Anopheles spp.,Culex spp., Drosophila melanegaster, Musca spp., Fannia spp., Calliphoraerythrocephala, Lucilia spp., Chrysomyia spp., Cuterebra spp.,Gastrophilus spp., Hyppobosca spp., Stomoxys spp., Oestrus spp.,Hypoderma spp., Tabanus spp., Tannia spp., Bibio hortulanus, Oscinellafrit, Phorbia spp., Pegomyia hyoscyami, Ceratitis capitata, Dacus oleaeand Tipula paludosa;

from the order of the Siphonaptera, for example Xenopsylla cheopis andCeratophyllus spp.;

from the class of the Arachnida, for example Scorpio maurus andLatrodectus mactans;

from the order of the Acarina, for example Acarus siro, Argas spp.,Ornithodoros spp., Dermanyssus gallinae, Eriophyes ribis, Phyllocoptrutaoleivora, Boophilus spp., Rhipicephalus spp., Amblyomma spp., Hyalommaspp., Ixodes spp., Psoroptes spp., Chorioptes spp., Sarcoptes spp.,Tarsonemus spp., Bryobia praetiosa, Panonychus spp. and Tetranychus spp.

The invention is illustrated by the following Examples.

Temperatures are in °C.

The pesticidal acitivity is assessed against houseflies and mustardbeetles by using the following techniques:

HOUSEFLIES (Musca domestica)

Female flies are treated on the thorax with a one microlitre drop ofinseticide dissolved in acetone. Two replicates of 15 flies are used ateach dose rate and 6 dose rates are used per compound under test. Aftertreatment, the flies are maintained at a temperature of 20°±1° and killis assessed 24 and 48 hours after treatment. LD₅₀ is values arecalculated in micrograms of inseticide per fly and relative toxicitiesare calculated from the inverse ratios of the LD₅₀ values (ee Sawicki etal, Bulletin of the World Health Organisation, 35, 893, (1966) andSawicki et al, Entomologia and exp. Appli. 10 253, (1967)).

MUSTARD BEETLES (Phaedon cochleariae Fab)

Acetone solutions of the test compound are applied ventrally to adultmustard beetles using a micro drop applicator. The treated insects aremaintained for 48 hours after which time kill is assessed. Tworeplicates of 40 to 50 mustard beetles are used at each dose level and 5dose levels are used for each compound. Again, LC₅₀ values arecalculated and relative potencies are calculated from the inverse ratiosof LD₅₀ (see Elliott et al, J. Sci. Food Agric. 20, 561, (1969)).

Relative potencies are calculated by comparison with5-benzyl-3-furylmethyl (1R)-trans-chrysanthemate (Bioresmethrin) whichis one of the more toxic chrysanthemate esters known to house flies andmustard beetles, it toxicity being about 24 times that of allethrin tohouseflies and 65 times that of allethrin to mustard beetles.

The invention is illustrated by the following Examples:

EXAMPLE 1 3-(2E,4-pentadienyl)benzyl(IR)cis-3-(2,2-biromovinyl)2,2-dimethylcyclopropanecarboxylate (a) Grignard reagent from 3-bromobenzaldehyde ethyleneacetal

Dry Mg (0.74 g) under dry N₂ in a flask is covered with THF (10 ml) anda crystal of I₂ added. 5 ml of a solution of 3-bromobenzaldehydeethylene acetal (7.0 g) in THF (30 ml) is added and kept until itbecomes warm, when it is cooled to 15°, and the remainder of the acetalsolution added over 15 minutes, then stirred for an additional 1 hour.

(b) 3(2E,4-pentadienyl)benzaldehyde

The Grignard reagent from 3-bromobenzaldehyde ethylene acetal (3.0 g) isadded to a mixture of 1-bromo-2E,4-pentadiene (2.2 g), copper (I)bromide(0.02 g) and THF (20 ml) cooled to -20°. This is allowed to warm to 20°with stirring over 1 hour.

The mixture is worked up as usual by addition of ammonium chloride andHPLC yields 0.05 g (22%), n_(D) ²⁰ 1.5723.

(c) 3(2E,4-pentadienyl)benzyl alcohol

The aldehyde (0.50 g) in ether is added to lithium aluminum hydride(0.08 g) in ether (20 ml) and the mixture is stirred at 20° for 1 hour.After successive dropwise additions of water (80 μl), 15% NaOH (80 μl)and water 240 μl), the resulting clear ether layer (and washings) isevaporated to a residue of 3-(2E,4-pentadienyl)benzyl alcohol. Yield0.48 g (95%), n_(d) ²⁰ 1.5654.

(d) 3-(2E,4-pentadienyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropane carboxylate

The alcohol (0.11 g) in benzene (5 ml) is added to (IR)cis3-(2,2-dibromovinyl)2,2-dimethylcyclopropanecarbonyl chloride (0.20 g)in benzene (5. ml). Pyridine (0.075 ml) is then added and the mixture isstirred at 20° for 16 hours. This is chromatographed on florisil and thefraction eluted by 7% ether in petrol evaporated to a residue of thetitle compound (0.20, 70%) n_(D) ²⁰ 1.5769.

EXAMPLE 23-(2Z,4-pentadienyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropanecarboxylate (a) 3(2-propynyl)benzaldehyde ethylene acetal

Dry Mg (0.74 g) under dry N₂ in a flask is covered with THF (10 ml) anda crystal I₂ added. 5 ml of a solution of 3-bromobenzaldehyde ethyleneacetal (7.0 g) in THF (30 ml) is added and kept until it becomes warm,when it is cooled to 15°, and the remainder of the acetal solution addedover 15 minutes, then stirred for an additional 1 hour. A mixture ofmethoxyallene (2.45 g), copper (1)chloride (0.30 g) and THF (30 ml) iscooled to -20°. The above Grignard solution (under moisture excludingconditions) is then added to this solution during 5 minutes, and allowedto warm to 20° with stirring over 30 minutes. Saturated aqueous ammoniumchloride is added and the product is extracted with ether. The etherlayer is washed with water, dried (MgSO4) and the residue distilled invacuo. Yield 4.3 g (75%) 89°-96° (0.03 m Hg), n_(D) ²⁰ 1.5422.

(b) 3(pent-4-en-2-ynyl)benzaldehyde ethylene acetal

Copper (1) iodide (0.10 g) tetrabistriphenylphosphine palladium (0)(0.60g) and n-butylamine (1.6 ml) are added to a solution of the acetylenicacetal (2.0 g) in benzene (50 ml) at 10°. Vinyl bromide (5 ml) is addedand the mixture stirred at 20° for 16 hours. This is evaporated underreduced pressure, the residue is extracted with carbon tetrachloride andchromatographed on florisil. The fraction eluted by 10% ether in petrolis collected. Yield 1.9 g (83%) n_(D) ²⁰ 1.5610.

(c) 3(2Z,4-pentadienyl)benzaldehyde

The enyne acetal (1.9 g) is stirred with zinc powder (75 g), potassiumcyanide (6.5 g) in a mixture of n-propanol and water (250 ml, 1:1) at20° under N₂ for 16 hours. This is filtered through celite and thefiltrate partitioned between ether and water. The organic layers arewashed with saturated aqueous NaCl, and dried (MgSO4). The residue istaken up in benzene (20 ml) and tetracyanoethylene (0.10 g) is added.This is stirred at 20° for 15 minutes, then passed down a florisilcolumn. The fraction eluted by 10% ether in petrol is collected. Thisresidue is hydrolysed by treatment with 3N HCl and the product purifiedby HPLC. Yield 0.23 g (15%) n_(D) ²⁰ 1.5613.

(d) 3(2Z,4-pentadienyl)benzyl alcohol

The aldehyde is reduced to the alcohol with lithium aluminum hydride,following the procedure of Example 1(c).

(e) 3(2Z,4-pentadienyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropane carboxylate

The alcohol is esterified by following the procedure of Example 1(d) toyield the ester, 88%, n_(D) ²⁰ 1.5710.

EXAMPLE 33-(Z-2-butenyl)benzyl(IR)cis-3-dibromovinyl)2,2-dimethylcyclopropanecarboxylate (a) 3(2-butynyl)benzaldehyde

The acetylenic acetal of Example 2(a) (1.5 g) in THF (10 ml) is cooledto -78° under N₂. A mixture of n-butyl lithium (5.1 ml, 1.55 m) (inhexane) and THF (7 ml) is added dropwise over 5 minutes, stirring iscontinued at -78° for 30 minutes. A mixture of methyl iodide (2.3 g) andTHF (4 ml) is then added over 2 minutes and the reaction mixture allowedto warm to 20° with stirring over 1 hour. Saturated aqueous ammoniumchloride is added and the organic layer evaporated under reducedpressure to a small residue of 3(Z2-butynyl)benzaldehyde ethyleneacetal. This is dissolved in THF (20 ml) and treated with 3N NCl (10 ml)at 20° for 1 hour. The product is partitioned between ether and water,and the ether layer washed with aq. NaHCO₃, H₂ O, dried (MgSO4). Theresidue is purified by preparative HPLC, yield 1.13 g (90%), n_(D) ²⁰1.5575.

(b) 3-(Z-2-butenyl)benzaldehyde

The acetylenic acetal of Example 3(a) (0.50 g) is dissolved in pyridine(15 ml). Palladium on Barium Sulphate (0.10 g) is added and the mixtureis stirred under an atmosphere of hydrogen until the uptake of H₂ceases. The mixture is filtered, THF (50 ml) and 3N HCl (150 ml) areadded to the filtrate and this is stirred at 20° for 1 hour. The THF isevaporated under reduced pressure and the product is extracted withether. The ether layer is washed with aq. Na HCO₃, H₂ O and dried(MgSO4). The residue is purified by prep. HPLC. Yield 0.20 g (50%),n_(D) ²⁰ 1.5389.

(c) 3-(Z-2-butenyl)benzyl alcohol

The aldehyde is reduced to the corresponding alcohol with lithiumaluminiun hydride by following the procedure of Example 1(c).

(d)3-(Z-2-butenyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropanecarboxylate

The alcohol is esterified by following the procedure of Example 1(d) toyield the ester, 76%, n_(D) ²⁰ 1.5627.

EXAMPLE 4 α-cyano3-(2Z,4-pentadienyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethycyclopropanecarboxylate (a) 3(2Z,4-pentadienyl)benzaldehyde cyanohydrin

3(2Z,4-pentadienyl)benzaldehyde produced as described in Example 2(c)(0.23 g) and potassium cyanide (0.40 g) in water (1.0 ml) and THF (4.0ml) are treated with 40% sulphuric acid (1.2 ml) with cooling to 3°-8°.After 1 hour at 20°, the reaction mixture is extracted with ether, whichis washed, dried and evaporated to a residue of3(2Z,4-pentadienyl)benzaldehyde cyanohydrin (0.25 g, 94%) n_(D) ²⁰1.5574.

(b)α-cyano-3(2Z,4-pentadienyl)benzyl(IR)cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropanecarboxylate

The cyanohydrin is esterified by following the procedure of Example 1(d)to yield the ester 26% n_(D) ²⁰ 1.5639.

EXAMPLES 5 TO 32

Table 1 sets out constants for esters (I) and intermediates (II, Y=OH)produced by following, with appropriate modification, the procedures ofExamples 1 to 4 together with bioassay results for esters (I). Theesters (I) are produced from intermediates (II) by following theprocedure of Example 1(d). Examples 1-4 are also included for ease ofreference.

The symbols B_(R) and C_(R) respectively represent the acid residues(R):

(IR)cis-2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropane carbonyl and(IR)trans-chrysanthemyl.

                                      TABLE I                                     __________________________________________________________________________    COMPOUNDS I AND II                                                                                                            Relative                                                                      potencies                                   B in             Procedure        (Bioresme-                    Ex.      Ring --CH.sub.2 CH═CHB                                                                  Ring    followed for                                                                             n.sub.D.sup.20 (II)                                                                 thrin = 100)                  No.                                                                              D  (A).sub.n                                                                        Position                                                                           (isomer) Position                                                                           R(I)                                                                             II(Example)                                                                          n.sub.D.sup.20 (I)                                                                m.p. (°C.)                                                                   HF  MB                        __________________________________________________________________________     5 H  H  --   --CH═CH.sub.2 (E)                                                                  3    C.sub.R                                                                          1      1.5362                                                                            1.5654                                                                              5   0.3                        1 H  H  --   --CH═CH.sub.2 (E)                                                                  3    B.sub.R                                                                          1      1.5679                                                                            1.5654                                                                              70  5                          6 CN H  --   --CH═CH.sub.2 (E)                                                                  3    C.sub.R                                                                          1 + 4  1.5338                                                                            1.5561                                                                              22  6.5                        7 CN H  --   --CH═CH.sub.2 (E)                                                                  3    B.sub.R                                                                          1 + 4  1.5673                                                                            1.5561                                                                              45  14                         8 H  H  --   --CH═CH.sub.2 (E)                                                                  4    B.sub.R                                                                          1      1.5764                                                                            41-41.5                                                                             51  1                          9 H  H  --   --CH═CH.sub.2 (Z)                                                                  3    C.sub.R                                                                          2      1.5355                                                                            1.5647                                                                              4   0.6                        2 H  H  --   --CH═CH.sub.2 (Z)                                                                  3    B.sub.R                                                                          2      1.5710                                                                            1.5647                                                                              90  7.3                       10 CN H  --   --CH═CH.sub.2 (Z)                                                                  3    C.sub.R                                                                          2 + 4  1.5296                                                                            1.5574                                                                              --  9                          4 CN H  --   --CH═CH.sub.2 (Z)                                                                  3    C.sub.R                                                                          2 + 4  1.5639                                                                            1.5574                                                                              170 14                        11 H  H  --   --CH═CH.sub.2 (Z)                                                                  4    B.sub.R                                                                          2      1.5714                                                                            1.5647                                                                              170 9                         12 H  H  --   --CH.sub.3 (Z)                                                                         3    C.sub.R                                                                          3      1.5211                                                                            1.5379                                                                              2.4 1.5                        3 H  H  --   --CH.sub.3 (Z)                                                                         3    B.sub.R                                                                          3      1.5627                                                                            1.5379                                                                              56  10                        13 CN H  --   --CH.sub.3 (Z)                                                                         3    C.sub.R                                                                          3 + 4  1.5143                                                                            1.5334                                                                              26  17                        14 CN H  --   --CH.sub.3 (Z)                                                                         3    B.sub.R                                                                          3 + 4  1.5507                                                                            1.5334                                                                              61  52                        15 H  H  --   -- CH.sub.3 (Z)                                                                        4    B.sub.R                                                                          3      1.5610                                                                            1.5367                                                                              30  3.0                       16 H  H  --   --CH.sub.2 CH.sub.3 (Z)                                                                3    C.sub.R                                                                          3      1.5176                                                                            1.5304                                                                              0.5 ca 0.2                    17 H  H  --   --CH.sub.2 CH.sub.3 (Z)                                                                3    B.sub.R                                                                          3      1.5575                                                                            1.5309                                                                              12  4                         18 CN H  --   --CH.sub.2 CH.sub.3 (Z)                                                                3    C.sub.R                                                                          3 + 4  1.5162                                                                            1.5292                                                                              34  12                        19 CN H  --   --CH.sub.2 CH.sub.3 (Z)                                                                3    B.sub.R                                                                          3 + 4  1.5533                                                                            1.5292                                                                              110 12                        20 H  H  --   --CH.sub.2 CH.sub.3 (Z)                                                                4    B.sub.R                                                                          3      1.5540                                                                            1.5277                                                                              34  3                         21 H  CH.sub.3                                                                         2    --CH═CH.sub.2 (E)                                                                  3    C.sub.R                                                                          1      1.5357                                                                            1.5680                                                                              1.8 0.6                       22 H  CH.sub.3                                                                         2    --CH═CH.sub.2 (E)                                                                  3    B.sub.R                                                                          1      1.5676                                                                            1.5680                                                                              4.5 7.7                       23 H  (CH.sub.3).sub.2                                                                 2,6  --CH═CH.sub.2 (E)                                                                  4    B.sub.R                                                                          1      1.5757                                                                            54-5  11  4.3                       24 H  CH.sub.3                                                                         2    --CH.sub.2 CH.sub.3 (Z)                                                                3    C.sub.R                                                                          3      1.5178                                                                            1.5370                                                                              1.4 0.7                       25 H  CH.sub.3                                                                         2    --CH.sub.2 CH.sub.3 (Z)                                                                3    B.sub.R                                                                          3      1.5573                                                                            1.5370                                                                              9.6 9.1                       26 H  CH.sub.3                                                                         2    H        3    C.sub.R                                                                          1      1.5219                                                                            1.5456                                                                              15  3.9                       27 H  CH.sub.3                                                                         2    H        3    B.sub.R                                                                          1      1.5645                                                                            1.5456                                                                              120 43                        28 H  (CH.sub.3).sub.2                                                                 2,6  H        3    C.sub.R                                                                          1      1.5232                                                                            1.5441                                                                              8.5 5.2                       29 H  (CH.sub.3).sub.2                                                                 2,6  H        3    B.sub.R                                                                          1      1.5637                                                                            1.5441                                                                              45  23                        30 H  (CH.sub.3).sub.2                                                                 2,6  H        4    B.sub.R                                                                          1      1.5608                                                                            1.5434                                                                              180 95                        31 CN H  --   H        3    C.sub.R                                                                          1 + 4  1.5218                                                                            1.5327                                                                              18  18                        32 CN H  --   H        3    B.sub.R                                                                          1 + 4  1.5549                                                                            1.5327                                                                              33  44                        __________________________________________________________________________

We claim:
 1. A compound of the formula: ##STR5## wherein Y representsOH;D represents hydrogen or a cyano group; B represents hydrogen or amethyl, ethyl or vinyl group; A represents methyl; n is 0, 1 or 2; withthe proviso that (1) when the CH₂ CH═CHB group is in the 4-position withrespect to the CHDY group, the D must be hydrogen and B must be methyl,ethyl or vinyl and the configuration about the double bond in the CH═CHBgroup must be Z and (2) when the group CH₂ CH═CHB is in the 3-positionwith respect to the CHDY group and D is CN, then n must be 0 and (3)when the group CH₂ CH═CHB is in the 2 or 3-position with respect to theCHDY group, then D is CN.
 2. A compound according to claim 1 wherein the--CH₂ CH═CHB group is in the 3 or 4 position.
 3. A compound according toclaim 1 wherein B represent H, A represents methyl and n is 1 or
 2. 4. Acompound according to claim 1 wherein B represents ethyl or vinyl andthe configuration at the double bond in --CH₂ CH═CHB is Z.
 5. A compoundaccording to claim 1 wherein D represents CN and the carbon atom towhich the CN group is bonded has substantially completely R orsubstantially completely S configuration.
 6. A compound according toclaim 1 which is alpha-cyano-3-(2,4-pentadienyl)benzyl alcohol or4-(2,4-pentadienyl)benzyl alcohol or alpha-cyano-3-(2-pentenyl)-benzylalcohol.